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<a href="heap__fixed__builder__capnp__msg__builder_8cpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow-IPC: Structured Transport</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright (c) 2023 Akamai Technologies, Inc.; and other contributors.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> * Each commit is copyright by its respective author or author&#39;s employer.</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> *</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * Licensed under the MIT License:</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> *</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * Permission is hereby granted, free of charge, to any person obtaining a copy</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> * of this software and associated documentation files (the &quot;Software&quot;), to deal</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> * in the Software without restriction, including without limitation the rights</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * copies of the Software, and to permit persons to whom the Software is</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * furnished to do so, subject to the following conditions:</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> *</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * The above copyright notice and this permission notice shall be included in</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * all copies or substantial portions of the Software.</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> *</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"> * THE SOFTWARE IS PROVIDED &quot;AS IS&quot;, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR</span></div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment"> * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"> * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span><span class="comment"> * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER</span></div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="comment"> * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="comment"> * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="comment"> * THE SOFTWARE. */</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="comment"></span> </div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="comment"></span> </div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span><span class="preprocessor">#include &quot;<a class="code" href="heap__fixed__builder__capnp__msg__builder_8hpp.html">ipc/transport/struc/heap_fixed_builder_capnp_msg_builder.hpp</a>&quot;</span></div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span> </div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceipc_1_1transport_1_1struc.html">ipc::transport::struc</a></div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span>{</div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span> </div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment">// Implementations.</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span> </div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a29e45b9263096e876754ea544031242d">   34</a></span><a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a29e45b9263096e876754ea544031242d">Heap_fixed_builder_capnp_message_builder::Heap_fixed_builder_capnp_message_builder</a></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span>  (flow::log::Logger* logger_for_blobs, <span class="keywordtype">size_t</span> segment_sz, <span class="keywordtype">size_t</span> frame_prefix_sz, <span class="keywordtype">size_t</span> frame_postfix_sz) :</div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span>  m_logger_for_blobs(logger_for_blobs),</div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span>  m_segment_sz(segment_sz), m_frame_prefix_sz(frame_prefix_sz), m_frame_postfix_sz(frame_postfix_sz)</div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span>{</div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span>  <span class="comment">// That&#39;s all for now.</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span>}</div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span> </div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a478c109e008dd33b04b605278c1b2a54">   42</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a478c109e008dd33b04b605278c1b2a54">Heap_fixed_builder_capnp_message_builder::emit_segment_blobs</a>(<a class="code hl_typedef" href="namespaceipc_1_1transport_1_1struc.html#a82a69eaa39cbe8a002de1266f1cbb5cb">Segment_ptrs</a>* target_blob_ptrs_ptr)</div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span>{</div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span>  <span class="comment">// We&#39;ll need to adjust it a bit below.</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span>  <span class="keyword">auto</span>&amp; blobs = <a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aad029fd4e08580a785824c48790c748f">m_serialization_segments_plus_frame_space</a>;</div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span>  <span class="keyword">auto</span>&amp; target_blob_ptrs = *target_blob_ptrs_ptr;</div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span> </div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span>  assert((!blobs.empty()) &amp;&amp; <span class="stringliteral">&quot;Should not be possible for serialization to be empty with our use cases.  Investigate.&quot;</span>);</div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span>  target_blob_ptrs.reserve(target_blob_ptrs.size() + blobs.size()); <span class="comment">// Remember: we are appending; not replacing.</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span> </div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span>  <span class="keyword">const</span> <span class="keyword">auto</span> capnp_segs = getSegmentsForOutput();</div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span>  assert((capnp_segs.size() == <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a8d4767193250d909cdf5b298f92f43e9">n_segments</a>())</div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span>         &amp;&amp; <span class="stringliteral">&quot;Somehow our MessageBuilder created fewer or more segments than allocateSegment() was called?!&quot;</span>);</div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span> </div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span>  <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> idx = 0; idx != capnp_segs.size(); ++idx)</div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span>  {</div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span>    <span class="comment">// Pointer-to-word + size in words =&gt; pointer-to-byte + size in bytes.</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span>    <span class="keyword">const</span> <span class="keyword">auto</span> capnp_seg = capnp_segs[idx].asBytes();</div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span>    <span class="keyword">const</span> <span class="keyword">auto</span> seg_sz = capnp_seg.size();</div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span> </div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span>    <span class="keyword">auto</span>&amp; blob = *(blobs[idx]);</div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span> </div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span>    assert((capnp_seg.begin() == blob.begin())</div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span>           &amp;&amp; <span class="stringliteral">&quot;Somehow capnp-returned segments are out of order to allocateSegment() calls; or something....&quot;</span>);</div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span>    assert((seg_sz != 0)</div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span>           &amp;&amp; <span class="stringliteral">&quot;capnp shouldn&#39;t be generating zero-sized segments.&quot;</span>);</div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span>    assert((seg_sz &lt;= (blob.capacity() - <a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#ac4e465bb2099093f06cd7e969d2e3de6">m_frame_prefix_sz</a> - <a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aa52369c664ada39cedb0a70f08880931">m_frame_postfix_sz</a>))</div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span>           &amp;&amp; <span class="stringliteral">&quot;capnp somehow overflowed the area we gave it.&quot;</span>);</div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span> </div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span>    blob.resize(seg_sz); <span class="comment">// Just pull up end() to immediately follow the serialization.</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span> </div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span>    <span class="comment">/* @todo Maybe output some stuff, like the segment dump, here, like</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment">     * shm::capnp_message_builder::lend() does?  Though, in practice, this is always the</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment">     * top serialization and hence is printed out in pretty good detail as the actual blob is transmitted over</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span><span class="comment">     * ipc::transport core layer.  So maybe skip it to avoid unneeded verbosity. */</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span> </div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span>    <span class="comment">/* Lastly output a *pointer*, as promised, to the Blob we hold.  They are free to do what they want</span></div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span><span class="comment">     * with the pointed-to `blob`, including sliding around its begin() and end() to make use of the</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span><span class="comment">     * frame space.  They must not access the dereferenced ptr past *this lifetime, nor past the</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="comment">     * next mutation (if any) (whichever happens first).  emit_segment_blobs() can be called agains after the</span></div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="comment">     * latter for an update serialization. */</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span>    target_blob_ptrs.push_back(&amp;blob);</div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span>  } <span class="comment">// for (idx in [0, size()))</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span>} <span class="comment">// Heap_fixed_builder_capnp_message_builder::emit_segment_blobs()</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span> </div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a766736906354f28d6ef2fa0752ba0e21">   86</a></span>kj::ArrayPtr&lt;capnp::word&gt; <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a766736906354f28d6ef2fa0752ba0e21">Heap_fixed_builder_capnp_message_builder::allocateSegment</a>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> min_sz) <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span>{</div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span>  <span class="keyword">using </span>Word = capnp::word;</div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span>  <span class="keyword">using </span>Capnp_word_buf = kj::ArrayPtr&lt;Word&gt;;</div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span>  <span class="keyword">using </span>flow::util::Blob;</div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span>  <span class="keyword">using </span>std::memset;</div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span>  <span class="keyword">constexpr</span> <span class="keywordtype">size_t</span> WORD_SZ = <span class="keyword">sizeof</span>(Word);</div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span> </div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span>  <span class="comment">/* It&#39;d be nice not to realloc m_serialization_segments_plus_frame_space&#39;s internal buffer, as that involves</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment">   * moving `unique_ptr&lt;Blob&gt;`s around: constant-time/cheap though it is, if we can avoid it, good.</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment">   * This value is pretty decent; 1 is really most typical, while 4 shallow `unique_ptr&lt;Blob&gt;`s is not a ton of RAM. */</span></div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span>  <span class="keyword">constexpr</span> <span class="keywordtype">size_t</span> N_SEGS_GUESS = 4;</div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span>  <a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aad029fd4e08580a785824c48790c748f">m_serialization_segments_plus_frame_space</a>.reserve(N_SEGS_GUESS); <span class="comment">// No-op after 1st time.</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span> </div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span>  <span class="comment">/* Background from capnp: They&#39;re saying the need the allocated space for serialization to store at least min_sz:</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment">   * probably they&#39;re going to store some object that needs at least this much space.  So typically it&#39;s some</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment">   * scalar leaf thing, like 4 bytes or whatever; but it could be larger -- or even huge (e.g., a Data or List</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment">   * of huge size, because the user mutated it so via a ::Builder).  Oh, and it has to be zeroed, as by calloc().</span></div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment">   *</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment">   * So all we *have* to allocate is min_sz exactly in that sense.  But the idea is to try to allocate more, so that</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment">   * capnp can efficiently shove more objects in there too without calling allocateSegment() for each one.</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment">   * And a fixed-heap builder we promised to make that the fixed size m_segment_sz.</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment">   * (MallocMessageBuilder has that mode too: FIXED_SIZE allocation-strategy.)  Of course, if min_sz exceeds that,</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment">   * then we have no choice but to allocate the larger amount min_sz. */</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span> </div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span>  <span class="keyword">const</span> <span class="keywordtype">size_t</span> seg_sz</div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span>    = std::max(min_sz * WORD_SZ, <span class="comment">// Don&#39;t forget: in their API min_sz is in `word`s.</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span>               <span class="comment">/* Seems prudent to give capnp an area that is a multiple of `word`s.  Maybe required.  Probably even.</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment">                * However we must *not* exceed m_segment_sz, if we can help it.  A little less is okay. */</span></div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span>               (<a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#af012d6917cdc16494a22b4b6f2c10edd">m_segment_sz</a> / WORD_SZ) * WORD_SZ);</div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span> </div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span>  <span class="comment">// Now just follow the logic we expounded on in the various doc headers.  Keeping explanations light here.</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span> </div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span>  <span class="comment">// By contract we can&#39;t let the prefix frame change the start of the area given to capnp to be non-aligned.</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span>  assert(((<a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#ac4e465bb2099093f06cd7e969d2e3de6">m_frame_prefix_sz</a> % <span class="keyword">sizeof</span>(<span class="keywordtype">void</span>*)) == 0)</div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span>         &amp;&amp; <span class="stringliteral">&quot;N=frame_prefix_sz passed to ctor, by contract, must be such that (aligned_ptr + N) is also aligned.&quot;</span>);</div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span> </div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span>  <a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aad029fd4e08580a785824c48790c748f">m_serialization_segments_plus_frame_space</a>.emplace_back(<span class="keyword">new</span> Blob(<a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#ae15044026ef19363177d474c6ac890bc">m_logger_for_blobs</a>));</div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span>  <span class="keyword">auto</span>&amp; blob = *(<a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aad029fd4e08580a785824c48790c748f">m_serialization_segments_plus_frame_space</a>.back());</div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span>  blob.reserve(<a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#ac4e465bb2099093f06cd7e969d2e3de6">m_frame_prefix_sz</a> + seg_sz + <a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aa52369c664ada39cedb0a70f08880931">m_frame_postfix_sz</a>);</div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span>  blob.resize(seg_sz, <a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#ac4e465bb2099093f06cd7e969d2e3de6">m_frame_prefix_sz</a>); <span class="comment">// Set: size(), start(), respectively.</span></div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span>  assert(blob.size() != 0);</div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span>  <span class="comment">// capnp requires: it must be zeroed.  (Blob intentionally doesn&#39;t zero.  @todo Would be a nice *optional* feature.)</span></div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span>  memset(blob.begin(), 0, blob.size());</div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span> </div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span>  <span class="keywordflow">return</span> Capnp_word_buf(<span class="keyword">reinterpret_cast&lt;</span>Word*<span class="keyword">&gt;</span>(blob.begin()),</div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span>                        <span class="keyword">reinterpret_cast&lt;</span>Word*<span class="keyword">&gt;</span>(blob.end()));</div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span>} <span class="comment">// Heap_fixed_builder_capnp_message_builder::allocateSegment()</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span> </div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno"><a class="line" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a8d4767193250d909cdf5b298f92f43e9">  135</a></span><span class="keywordtype">size_t</span> <a class="code hl_function" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a8d4767193250d909cdf5b298f92f43e9">Heap_fixed_builder_capnp_message_builder::n_segments</a>()<span class="keyword"> const</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span><span class="keyword"></span>{</div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span>  <span class="keywordflow">return</span> <a class="code hl_variable" href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aad029fd4e08580a785824c48790c748f">m_serialization_segments_plus_frame_space</a>.size();</div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span>  <span class="comment">// Note this equals getSegmentsForOutput().size().  emit_segment_blobs() as of this writing assert()s as much.</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span>}</div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span> </div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span>} <span class="comment">// namespace ipc::transport::struc</span></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_a29e45b9263096e876754ea544031242d"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a29e45b9263096e876754ea544031242d">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::Heap_fixed_builder_capnp_message_builder</a></div><div class="ttdeci">Heap_fixed_builder_capnp_message_builder(flow::log::Logger *logger_for_blobs, size_t segment_sz, size_t frame_prefix_sz, size_t frame_postfix_sz)</div><div class="ttdoc">Constructs the message-builder, with the policy to allocate the segments in a particular way,...</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8cpp_source.html#l00034">heap_fixed_builder_capnp_msg_builder.cpp:35</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_a478c109e008dd33b04b605278c1b2a54"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a478c109e008dd33b04b605278c1b2a54">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::emit_segment_blobs</a></div><div class="ttdeci">void emit_segment_blobs(Segment_ptrs *target_blob_ptrs)</div><div class="ttdoc">Returns pointers to Blobs which are the serialization segments at this time.</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8cpp_source.html#l00042">heap_fixed_builder_capnp_msg_builder.cpp:42</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_a766736906354f28d6ef2fa0752ba0e21"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a766736906354f28d6ef2fa0752ba0e21">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::allocateSegment</a></div><div class="ttdeci">kj::ArrayPtr&lt;::capnp::word &gt; allocateSegment(unsigned int min_sz) override</div><div class="ttdoc">Implements MessageBuilder API.</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8cpp_source.html#l00086">heap_fixed_builder_capnp_msg_builder.cpp:86</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_a8d4767193250d909cdf5b298f92f43e9"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#a8d4767193250d909cdf5b298f92f43e9">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::n_segments</a></div><div class="ttdeci">size_t n_segments() const</div><div class="ttdoc">Returns what target_blob_ptrs.size() would return after calling emit_segment_blobs(&amp;target_blob_ptrs)...</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8cpp_source.html#l00135">heap_fixed_builder_capnp_msg_builder.cpp:135</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_aa52369c664ada39cedb0a70f08880931"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aa52369c664ada39cedb0a70f08880931">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::m_frame_postfix_sz</a></div><div class="ttdeci">const size_t m_frame_postfix_sz</div><div class="ttdoc">See ctor.</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8hpp_source.html#l00189">heap_fixed_builder_capnp_msg_builder.hpp:189</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_aad029fd4e08580a785824c48790c748f"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#aad029fd4e08580a785824c48790c748f">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::m_serialization_segments_plus_frame_space</a></div><div class="ttdeci">std::vector&lt; boost::movelib::unique_ptr&lt; flow::util::Blob &gt; &gt; m_serialization_segments_plus_frame_space</div><div class="ttdoc">Before emit_segment_blobs(), stores each segment allocated as requested by capnp via allocateSegment(...</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8hpp_source.html#l00199">heap_fixed_builder_capnp_msg_builder.hpp:199</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_ac4e465bb2099093f06cd7e969d2e3de6"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#ac4e465bb2099093f06cd7e969d2e3de6">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::m_frame_prefix_sz</a></div><div class="ttdeci">const size_t m_frame_prefix_sz</div><div class="ttdoc">See ctor.</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8hpp_source.html#l00187">heap_fixed_builder_capnp_msg_builder.hpp:187</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_ae15044026ef19363177d474c6ac890bc"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#ae15044026ef19363177d474c6ac890bc">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::m_logger_for_blobs</a></div><div class="ttdeci">flow::log::Logger * m_logger_for_blobs</div><div class="ttdoc">See ctor.</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8hpp_source.html#l00183">heap_fixed_builder_capnp_msg_builder.hpp:183</a></div></div>
<div class="ttc" id="aclassipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder_html_af012d6917cdc16494a22b4b6f2c10edd"><div class="ttname"><a href="classipc_1_1transport_1_1struc_1_1Heap__fixed__builder__capnp__message__builder.html#af012d6917cdc16494a22b4b6f2c10edd">ipc::transport::struc::Heap_fixed_builder_capnp_message_builder::m_segment_sz</a></div><div class="ttdeci">const size_t m_segment_sz</div><div class="ttdoc">See ctor.</div><div class="ttdef"><b>Definition:</b> <a href="heap__fixed__builder__capnp__msg__builder_8hpp_source.html#l00185">heap_fixed_builder_capnp_msg_builder.hpp:185</a></div></div>
<div class="ttc" id="aheap__fixed__builder__capnp__msg__builder_8hpp_html"><div class="ttname"><a href="heap__fixed__builder__capnp__msg__builder_8hpp.html">heap_fixed_builder_capnp_msg_builder.hpp</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html">ipc::transport::struc</a></div><div class="ttdoc">Sub-module of Flow-IPC module ipc::transport providing transmission of structured messages specifical...</div><div class="ttdef"><b>Definition:</b> <a href="ipc__transport__structured_2src_2ipc_2transport_2struc_2channel_8cpp_source.html#l00030">channel.cpp:31</a></div></div>
<div class="ttc" id="anamespaceipc_1_1transport_1_1struc_html_a82a69eaa39cbe8a002de1266f1cbb5cb"><div class="ttname"><a href="namespaceipc_1_1transport_1_1struc.html#a82a69eaa39cbe8a002de1266f1cbb5cb">ipc::transport::struc::Segment_ptrs</a></div><div class="ttdeci">std::vector&lt; flow::util::Blob * &gt; Segment_ptrs</div><div class="ttdoc">Sequence of 1+ Blob pointers to blobs which must stay alive while these pointers may be dereferenced,...</div><div class="ttdef"><b>Definition:</b> <a href="struc__fwd_8hpp_source.html#l00122">struc_fwd.hpp:122</a></div></div>
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